改性TiO2-x/N掺杂石墨烯量子点纳米异质结的界面调控及光催化性能研究

改性TiO2-x光催化剂具有无毒、低成本和可见光响应等优点，但其在紫外光区乃至全光谱下量子效率的降低以及过量引入缺陷引发的光生载流子复合等问题，严重限制了其在光催化领域的应用。此外，由于特殊结晶/非晶核壳结构的存在，改性TiO2-x表面是否仍具有选择性光催化作用尚未十分明确。为进一步提高改性TiO2-x的光生电子转移驱动力，基于掺杂、晶面及界面调控等设计策略，本项目提出构筑改性TiO2-x与N掺杂石墨烯量子点(NGQDs)纳米异质结光催化体系：改性TiO2-x显著减小的带隙宽度，拓宽了自身可见光吸收范围；NGQDs具有较大比表面积，且能通过改变尺寸和表面功能化等手段调节自身带隙宽度和荧光性质，并实现对不同分子的吸附和键合。通过研究改性TiO2-x表面对NGQDs的选择性吸附/键合情况，优化二者协同作用，有望大幅提高材料的光生载流子界面迁移效率，获得新型安全高效可见光响应光催化剂。

Modified TiO2-x prepared via defects self-doping modification of pristine white TiO2 was intensively researched, due to its nontoxicity, low cost and visible-light responsive properties. However, the quantum efficiency of modified TiO2-x decreases under ultraviolet light or even the whole solar spectrum, and it would suffer high recombination rate of photo-generated carriers with excess defects. These disadvantages restrict further enhancement of their photocatalytic activity. In addition, due to the special crystal/amorphous core/shell structure, it is still uncertain whether the surface of TiO2-x would have an influence on its selective photocatalytic mechanism. To improve the transfer rate of photo-generated electrons in TiO2-x, modified TiO2-x/N doped-graphene quantum dots (NGQDs) heterojunction photocatalysts were fabricated, based on doping, lattice and interfacial modification strategies: The obviously reduced band gap of TiO2-x can extend its light responsive range. On the other hand, NGQDs have a relatively large specific surface area, and it is easy to change its band gap and fluorescence properties through size control or surface function. Different surface functional groups of NGQDs could also realize particular molecular absorption/bonding abilities. This project is aiming to clarify possible bonding between TiO2-x and NGQDs through self-modification of TiO2 and interfacial modification of TiO2-x/NGQDs heterojunction, and optimize the synergistic effect of two different semiconductors, thus improving the heterojunction’s visible-light absorption and interfacial transfer rate of photo-generated carriers and leading to a new, safe and efficient visible-light driven photocatalyst.